The present invention relates to a wellhead component having an access port through which coiled tubing can be inserted into the bore of the tubing string or, alternatively, into the annulus between the tubing string and the production casing of a well.
Canadian patent No. 2,197,584 discloses a wellhead component which is referred to as a composite pumping tree. This pumping tree is shown in FIG. 1. It typically is used by incorporating it into a wellhead equipped with a rotary drive assembly for rotating a rod string connected with a downhole rotary or screw pump (see FIGS. 4 and 5).
This known pumping tree a comprises a monolithic housing b formed from a single piece of steel. It may be forged or cast. The housing has a vertical bore c extending therethrough and comprises:
a bottom connection d, which can be studded or flanged or of the threaded ring or clamp and hub type. The bottom connection is operative to connect with the top connection of the wellhead tubing head;
a production blowout preventer (xe2x80x9cBOPxe2x80x9d) housing section e forming side openings f communicating with the vertical bore c, for receiving the ram components g of a BOP;
a flow tee section h forming at least one side opening i communicating with the bore c, for producing well fluid; and
a top connection j, preferably studded and internally threaded, for connecting with the stuffing box and frame of a rotary drive assembly for sealing and rotating the rod string.
The pumping tree a is free of narrow necks and has a substantially consistently thick side wall k.
The wellhead assembly shown in FIG. 1 is commonly used in connection with wells producing heavy oil from a sand formation. With some of these wells it is necessary to periodically insert a small diameter coiled tubing string into the production tubing string bore or into the annulus between the tubing string and the production casing. This may be done, for example, for the purpose of circulating fluid through the well to wash out sand bridges or plugs which have built up downhole. Alternatively, there are also occasions when it may be desirable to run pressure or temperature measuring instruments into the well on coiled tubing.
In the past, when a coiled tubing string or instrumentation string was to be run into a well, it was the conventional practice:
to unbolt and remove the rotary drive assembly; and
then mount a special spool in its place, the spool having one or more angled side ports through which the coiled tubing or instrumentation string could be inserted.
This prior practice was time consuming and involved cost. It also produced a relatively high assembly which a service rig might not correlate with.
In accordance with the present invention, a composite pumping tree is modified by providing an access port extending inwardly and downwardly through the side wall from the tree""s outer surface to either the vertical bore or to the tree""s bottom surface. The access port terminating at the vertical bore makes it possible to insert a coiled tubing string into the bore of the tubing string. The access port terminating at the bottom surface of the tree, when coupled with an opening extending through the tubing string hanger, enables insertion of coiled tubing into the annulus between the production casing and tubing string. Preferably an inlet pipe extends upwardly and outwardly from the access port. The inlet pipe may be a nipple threaded into the access port or it may be integral with the tree. A control valve is mounted to the inlet pipe.
The main advantages of the assembly are that:
it does away with the need to first remove the bulky rotary drive assembly and then insert a spool, when coiled tubing is to be inserted; and
it keeps the access port relatively low, so that the service rig equipment is better able to work with it.